Hydraulically actuated implement systems of many different types are used in a broad variety of machines. Track-type tractors, backhoes, excavators, and wheel loaders are notable examples, having hydraulically actuated implement systems for digging, dozing, loading, spreading and all manner of other activities relating to manipulation of loose material and various other types of loads. Controlling a hydraulically actuated implement system with even reasonable efficiency and accuracy is by no means a simple task. Operators are typically tasked with manually manipulating various control levers while monitoring multiple operating conditions of the machine, whether stationary or traveling. It is thus unsurprising that even highly skilled operators with decades of experience are often able to improve performance with the assistance of various electronically controlled features of hydraulically actuated implement systems.
Over the years, engineers have proposed a great many different strategies for automating work cycles or parts thereof, such as material loading cycles whereby a machine captures, lifts and dumps material. Rather than requiring an operator to manually and repetitiously raise and lower the machine's lift arms, control tilting of the machine's bucket, and monitor and control the travel path and speed of the machine itself, a computer controls some or all of the functions of the implement system so that an operator can focus his attention elsewhere, or simply avoid fatigue.
Other examples of computer controlled processes include grading, trenching, and virtually any other common activity which can be performed by a human operator. Despite substantial advances in automated machine process technology, there nevertheless remain many instances where skilled operators can best computers in relation to at least certain aspects of a machine process, or where handing over control of an implement system to a computer for the totality of a work cycle is undesirable for other reasons. In still other instances, designing and implementing computer control for all aspects of a work cycle has proven to be very challenging, and often unnecessary to achieve real world efficiency gains. There thus remain ample opportunities for automating parts of machine work cycles, while leaving other parts to be controlled conventionally by an operator or by a separate control routine.
One example of an automated control strategy for a construction machine is known from U.S. Pat. No. 5,052,883 to Morita et al. In Morita et al., a work vehicle has an implement position controller. The controller is configured to automatically orient and position an implement, such as a bucket coupled with a linkage in a wheel loader. While Morita et al. appears to be an elegant strategy for attaining a pre-defined bucket orientation and position, especially for certain types of work cycles, there is always room for improvement, especially as new problems are recognized or created.